The over-budget spending on ICE Air that John just described is just one of the extra costs of the immigration crackdown throughout the federal government, and NPR's Joel Rose has been tracking that spending. Hi there, Joel.

JOEL ROSE, BYLINE: Hi, Steve.

INSKEEP: What other extra costs are there?

ROSE: Well, if you think about the planes that John was describing in that piece as sort of the end of the process, there's a lot that happens before you get to that point, right? More immigrants are being detained inside the U.S. Migrants are still showing up at the Southwest border in big numbers. And all of those immigrants and migrants are being detained by the Department of Homeland Security, and many are being deported back to their home countries. All of that costs money. And the budget for DHS, which includes Immigration and Customs Enforcement, is upwards of $47 billion. ICE's budget included a record $3 billion just for custody operations. But that still has not been enough. The administration is asking for a similar amount of money for this year in a bill that is currently being debated on Capitol Hill.

INSKEEP: Where is ICE getting this extra money when they've clearly spent more than Congress had allocated for this?

ROSE: Well, in the short-term, they're just moving money around. Last month, DHS said that they've reallocated about $200 million from their current-year budget away from things like the Coast Guard and FEMA operations in order to cover ICE and its over-budget removal operations.

INSKEEP: FEMA, that's the Federal Emergency Management Agency, which responds to things like Hurricane Florence the other day. Is it unusual that you would rob FEMA, so to speak, to pay for immigration?

ROSE: Actually, it's not. I mean, agencies do things like this all the time, right? The Obama administration did the same thing when a surge of unaccompanied children arrived from Central America without their parents at the border in 2014. Border agents can't turn them away under the law so the administration had this unexpected expense of caring for these kids. And now something similar is happening again. The Department of Health and Human Services is caring for a record number of unaccompanied children in government-funded shelters. And HHS has had to move about $260 million from other parts of its budget to cover that. That includes money that was originally intended for the Centers for Disease Control and the National Cancer Institute.

INSKEEP: Cancer research is being slighted for this. So can agencies continue improvising their way to the end of this policy?

ROSE: Maybe in the short-run. But in the long-run, there are some major costs that you can't just reallocate your way out of. I mean, we've heard about the children who are separated from their parents at the border. Now the Department of Homeland Security wants to detain family units together indefinitely while their legal cases play out. There may be legal hurdles to doing that, but leaving that aside, it's going to cost a lot of money to detain those families. And it's the kind of money you may not be able to find by just reallocating it from somewhere else in the budget. It's something that Congress maybe really will have to authorize more money for.